I'm curious how websites like bitref.com can determine the balance of a bitcoin wallet very quickly.
I understand that the blockchain stores every single transaction across the thousands of blocks, so it's possible to reconstruct the balance of any wallet with this ledger. But wouldn't it take a long time to scan all these transactions?
Instead, does the blockchain actually store every single address in some sort of map? Would this also contain the balance of each address? If so, I can't find a website where I could view all the addresses on the blockchain. Does anyone know where I can find that?